Restrict parsing of nullable Bool values to `""`, `false`, and `true`

[gdavison]

Description

In order to simulate values that support Boolean values that can also be unset, the provider currently uses TypeNullableBool which is implemented as a TypeString with special validation and parsing rules to restrict to boolean values.

The parsing rules for TypeNullableBool currently allow 0 and 1 as valid values, matching behaviour of very old versions of Terraform. Only allow the values "", false, and true.

Note: The ideal solution is to update the resources to use terraform-plugin-framework instead of terraform-plugin-sdk/v2. terraform-plugin-framework allows typed nullable values.

The previous parsing behaviour was deprecated in #29378.

Affected Resource(s) and/or Data Source(s)

No response

Potential Terraform Configuration

No response

References

No response

Would you like to implement a fix?

None

[github-actions[bot]]

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